Identification of antioxidants for prevention of peroxide-mediated oxidation of recombinant human ciliary neurotrophic factor and recombinant human nerve growth factor.

Peroxides present in non-ionic surfactants used to stabilize certain recombinant protein formulations (e.g. polysorbate 80) can result in the oxidative degradation of proteins. In this study, the ability of various pharmaceutically acceptable antioxidants to prevent the oxidative degradation of two therapeutic proteins, recombinant human Ciliary Neurotrophic Factor (rhCNTF) and recombinant human Nerve Growth Factor (rhNGF), caused by alkyl hydroperoxides and hydrogen peroxide was studied. For rhCNTF, the rank order of effectiveness of the antioxidants tested was: thiols (cysteine, glutathione, thioglycerol) >> thioethers (methionine). Other parenterally acceptable antioxidants (ascorbic acid, propyl gallate and sodium bisulfite) destabilized the protein. The thiol antioxidants (cysteine and glutathione) were also the most effective antioxidants for rhNGF; however, in contrast to rhCNTF, ascorbic acid did not destabilize rhNGF. The rank order of effective antioxidants for rhNGF was: thiols (cysteine, glutathione) > > thioethers (methionine) > ascorbic acid.